“As a country that talks a big game about valuing human rights and setting a model for others across the globe, we should be ashamed of ourselves when domestically, the United States continues to execute prisoners,” said Steven W. Hawkins, a former attorney for inmates on death row who serves as executive director of Amnesty USA.

Wood’s death comes three months after the botched execution in Oklahoma of killer Clayton Lockett, who reportedly writhed in pain after he was given the first part of a three-drug lethal cocktail and ultimately died of a heart attack.

President Obama called the mishap “deeply troubling” and ordered a federal review not just of the issues at play in the Oklahoma case, but also the application of the death penalty generally.

"Racial bias. Uneven application of the death penalty. Situations in which there were individuals on death row who later on were discovered to be innocent … all of these do raise significant questions about how the death penalty is being applied," Obama said in May. “I think as a society, we have to ask ourselves some difficult and profound questions.”

Even before the Lockett case, the Justice Department had imposed a moratorium on federal executions while the agency studies policies employed by the Federal Bureau of Prisons.

Following Obama’s order, that review was expanded, “to include a survey of state-level protocols and related policy issues,” the Justice Department said.

“The department’s review of the federal protocol used by the Bureau of Prisons and other related policy issues is underway and ongoing,” an agency spokeswoman said.

The agency declined to say whether the Wood case would be part of the probe.

Earlier this year, a The Constitution Project’s Death Penalty Committee, a bipartisan group of experts, formed to assess the state of the death penalty and issued a reportcalling for a host of changes to the system.

Among them were the proposed establishment of an office at the Justice Department tasked with reviewing innocence claims of death row inmates.

The group also urged the development of “federal standards and procedures” for accrediting forensic laboratories, and said states should only use drugs that were approved by regulators at the Food and Drug Administration.

The report cited research has called into question the practices used in some of the 32 states that employ the death penalty, and said many state policies lacked transparency.

"Our governments must not be permitted to conceal this ultimate act of government power from the light of day,” said former Texas Gov. Mark White (D), a supporter of the death penalty who was a co-chairman on the task force.

“Difficulty in obtaining drugs for executing people has led our state governments down a dangerous path — a path which appears to have resulted in yet another preventable miscarriage of justice,” he said this week.